The conventional wrinkled band has a band 100 having a constant vertical width. An air-expansion tube 100, which is expanded to have substantially the same width as the vertical width of the band, is fixed inside the band 100 by means of a sewing means. Thereafter, the air of the air-expansion tube 110 is removed such that the band 100 is transformed into a wrinkled band.
This conventional technique is disclosed in Korean Patent No. 142202. Each upright air-expansion tube 110 is vertically connected to each connector 120 in a single direction. The connector 120 is not to be expanded. Thereafter, only the air-expansion tube 110 is housed in a separate pocket 130 with the air-expansion tube 110 being expanded. Then, the pocket 130 is connected, using a sewing means, to a band 100 having substantially the same width as the expanded air-expansion tube 110. The air of the air-expansion tube 110 is removed to thereby provide a wrinkled band. However, disadvantageously this technique needs many connectors, and the connection of the air-expansion tube 110 to the connector 120 is manually carried out using a pressuring band 140. In addition, when these many connector 120 is expanded by a strong air pressure, the connection portion between the connector 120 and the air-expansion tube 110 is prone to be burst, or air-leakage is occurred due to non-uniform pressuring.
Therefore, in order to solve these problems, recently, Korean Patent No. 298328 has proposed a technique, in which a single air-expansion tube 210 is formed in zigzags and placed inside a band 200 having a constant width. After that, the air-expansion tube 210 is seal-adhered to the band 200 using a sewing means, while the air-expansion tube 210 is expanded by air-injection.
However, as one disadvantage of the above approach, when the single air-expansion tube 210 is formed in zigzags, a curved portion 220 is created in the upper and lower portion thereof. In the case where this curved portion is formed closely to each other, the upper and lower curved portion 220 is folded, and thus the air-injection is impeded due to the folding of the curved portion. In order to avoid the folding of the curved portion 220, the spacing 230 between the curved portions is made larger, a strong force cannot be achieved, thereby failing to obtain a desired effect.
In addition, since this separate air-expansion tube 210 is accommodated inside the band 200, when wearing the band in the waist, the user feels a sense of foreign matters with the air-expansion tube 210 being expanded. Since the width of the wrinkled band 200 is larger in the center portion thereof, as compared with both end portions thereof, the both end portions having a relatively narrower width is stretched when the center portion thereof is extended. Therefore, the center portion of the band is likely to be flipped backwards, thereby deteriorating a comfort sense of wearing.